This function provides control over the memory used as a stack at run-time by a call to pcre[16|32]_exec() with a pattern that has been successfully compiled with JIT optimization. The arguments are:

extra the data pointer returned by pcre[16|32]_study() callback a callback function data a JIT stack or a value to be passed to the callback function

If callback is NULL and data is NULL, an internal 32K block on the machine stack is used.

If callback is NULL and data is not NULL, data must be a valid JIT stack, the result of calling pcre[16|32]_jit_stack_alloc().

If callback not NULL, it is called with data as an argument at the start of matching, in order to set up a JIT stack. If the result is NULL, the internal 32K stack is used; otherwise the return value must be a valid JIT stack, the result of calling pcre[16|32]_jit_stack_alloc().

You may safely assign the same JIT stack to multiple patterns, as long as they are all matched in the same thread. In a multithread application, each thread must use its own JIT stack. For more details, see the pcrejit page.

There is a complete description of the PCRE native API in the pcreapi page and a description of the POSIX API in the pcreposix page.